Physical Sciences and Mathematics Commons^™

Fault Arrangements And Their Effect On The Performance Of Wireless Sensor Networks, Dwayne Sayone Blai

Electrical & Computer Engineering Theses & Dissertations

Wireless sensor networks face many reliability challenges. The networks are deployed in open, hostile environments, making them easily susceptible to network failure. As a result, there are countless faults that can occur in sensor networks, from component failure to outside attacks. Outside attacks take place when an adversary gains control over a node or set of nodes in the network. Outside attackers can destroy a network in numerous ways such as random attacks, clustering attacks, search-based attacks, etc. The method and strategy used in each of these attacks directly affects the network's reliability. Understanding how these adversaries are positioned is …

An Operational Model For Mobile Sensor Cloud Management, Indrajeet Kalyankar

Electrical & Computer Engineering Theses & Dissertations

Mobile sensors provide a safe, cost effective method for gathering information in hazardous environments. When the hazardous environment is either unexplored, such as the surface of Mars, or unanticipated, such as the result of chemical contamination, it is desirable for a system to gather information with a minimal amount of outside control (localization, decision control, etc.) and prepositioned sensors. If one takes a look at the number of the sensors deployed on a scale, at the lower end is the sole, multipurpose sensor unit. The upper end deals with hordes of inexpensive, expendable sensors. In the middle, a cluster of …

Learning As A Nonlinear Line Of Attraction For Pattern Association, Classification And Recognition, Ming-Jung Seow

Electrical & Computer Engineering Theses & Dissertations

Development of a mathematical model for learning a nonlinear line of attraction is presented in this dissertation, in contrast to the conventional recurrent neural network model in which the memory is stored in an attractive fixed point at discrete location in state space. A nonlinear line of attraction is the encapsulation of attractive fixed points scattered in state space as an attractive nonlinear line, describing patterns with similar characteristics as a family of patterns.

It is usually of prime imperative to guarantee the convergence of the dynamics of the recurrent network for associative learning and recall. We propose to alter …

Gaussian Mixture Models And Neural Networks For Automatic Speaker Identification, Usha Gayatri Chalkapally

Electrical & Computer Engineering Theses & Dissertations

Automatic Speaker Recognition is the process of automatically recognizing who is speaking on the basis of individual information contained in speech signals. This technique of Automatic Speaker Recognition makes it possible to use the speaker's voice to verify their identity and control access to services such as voice dialing, banking by telephone, telephone shopping, database access services, information services, voice mail, security control for confidential information areas, and remote access to computers.

In this thesis, the techniques of Gaussian Mixture Models and Neural Networks for Automatic Speaker Identification are presented. Algorithms for Speaker Identification using Gaussian Mixture Models were developed, …

An Adaptive Algorithm To Identify Ambiguous Prostate Capsule Boundary Lines For Three-Dimensional Reconstruction And Quantitation, Rania Yousry Hussein

Electrical & Computer Engineering Theses & Dissertations

Currently there are few parameters that are used to compare the efficiency of different methods of cancerous prostate surgical removal. An accurate assessment of the percentage and depth of extra-capsular soft tissue removed with the prostate by the various surgical techniques can help surgeons determine the appropriateness of surgical approaches. Additionally, an objective assessment can allow a particular surgeon to compare individual performance against a standard. In order to facilitate 3D reconstruction and objective analysis and thus provide more accurate quantitation results when analyzing specimens, it is essential to automatically identify the capsule line that separates the prostate gland tissue …

The Reliability Of The Computer Communication Networks Including Mobile Nodes, Sahin Yasar

Electrical & Computer Engineering Theses & Dissertations

The wireless computer networks have an uncertainty in their structures aside from their big advantages for the users. The environmental conditions, changing locations of the mobile hosts and the changing components in the system can easily affect their reliability. In order to know a system capability performing its functions, keep the reliability at a certain level and/or detect the deficiency of the system, it is necessary to analyze the reliability of a computer communication network including the wired and wireless parts. But the above reasons also make the analysis and a unique solution difficult so a set of algorithms is …

Whole Word Phonetic Displays For Speech Articulation Training, Fansheng Meng

Electrical & Computer Engineering Theses & Dissertations

The main objective of this dissertation is to investigate and develop speech recognition technologies for speech training for people with hearing impairments. During the course of this work, a computer aided speech training system for articulation speech training was also designed and implemented. The speech training system places emphasis on displays to improve children's pronunciation of isolated Consonant-Vowel-Consonant (CVC) words, with displays at both the phonetic level and whole word level. This dissertation presents two hybrid methods for combining Hidden Markov Models (HMMs) and Neural Networks (NNs) for speech recognition. The first method uses NN outputs as posterior probability estimators …

A Non-Linear Technique For The Enhancement Of Extremely Non-Uniform Lighting Images, Ender Oguslu

Electrical & Computer Engineering Theses & Dissertations

At night scenes, either the low intensity areas that are under poor light or the high intensity areas that are overexposed cannot be clearly seen. Various image processing techniques have been developed to recover the meaningful information under extremely low lighting conditions. Among these, the algorithms based on integrated neighborhood dependency of pixel characteristics and based on the illuminance reflectance model perform well for improving the visual quality of digital images captured under nonuniform and extremely low lighting conditions. Although these techniques perform well in low lighting conditions, they cannot perform well in overexposed regions under dark environments such as …

Mobius: An Omnidirectional Robotic Platform And Software Architecture For Network Teleoperation, Samuel Aaron Miller

Electrical & Computer Engineering Theses & Dissertations

The following thesis presents the results of a project to develop and test an omnidirectional robotic system (hardware and software) at NASA Langley Research Center's Robotics and Intelligent Machines Lab. The impetus for the project was the unique capabilities of omnidirectional systems. Some of the many potential benefits these systems have include improved material-handling capabilities in constrained environments (such as might be found in extraterrestrial manned habitats), efficient camera-based vehicle teleoperation, and simplified route planning for autonomous robot operations.

The project's focus was to design, build, and test a system that used Mecanum wheels to achieve omnidirectional motion. In addition …

Characterization And Quantum Efficiency Validation Of Ingaas Linear Focal Plane Array, Christopher Salenga Garcia

Electrical & Computer Engineering Theses & Dissertations

A 1x1024 InGaAs linear hybrid focal plane array (FPA) with CMOS readout was characterized at room temperature to analyze its electrical and optical properties and to measure its performance parameters.

The most important parameter of an FPA is the gain constant K, which allows conversion of the FPA output measurement unit from digital counts into the number of generated signal electrons. For FPAs with CMOS readout, the commonly used meanvariance method for determining K often underestimates its value. A more reliable method for finding K is the photon transfer technique, which is developed for FPAs with CCD readout. This …

Femtosecond Laser Ablation With Single And Two-Photon Excitation For Mems, Mohamed Abdelfattah Kottb Ahmad Elbandrawy

Electrical & Computer Engineering Theses & Dissertations

There is an increasing interest in femtosecond laser micromachining of materials because of the femtosecond laser's unique high peak power, ultrashort pulse width, negligible heat conductivity process during the laser pulse, and the minimal heat affected zone, which is in the same order of magnitude of the ablated submicron spot. There are some obstacles in reaching optimal and reliable micromachining parameters. One of these obstacles is the lack of understanding of the nature of the interaction and related physical processes. These processes include amorphization, melting, re-crystallization, nucleated-vaporization, and ablation.

The focus of this Dissertation was to study the laser-matter interaction …